Water Dependence Risks for America’s Aging Coal Fleet

The Union of Concerned Scientists identifies hundreds of U.S. coal generators as 'ripe for retirement' due to high operating costs and vulnerability to 'energy-water collisions.' Many of these plants rely on once-through cooling systems that withdraw massive amounts of water and are subject to strict EPA temperature discharge limits. The report argues that replacing these aging plants with renewables or energy efficiency would significantly reduce national water withdrawals and consumption, particularly in states like Alabama, Maryland, Michigan, and Wisconsin.

• The Union of Concerned Scientists identified 295 coal generators, totaling 52 GW of capacity, as 'ripe for retirement' as of March 2013, meaning they are more expensive to operate than efficient natural gas combined cycle (NGCC) plants or wind power facilities after accounting for pollution controls.
• Water dependence creates operational risks known as 'energy-water collisions,' where insufficient or overheating cooling water forces plants to reduce power generation during peak demand, such as during the 2007 and 2008 heat waves in North Carolina.
• A significant portion of the 'ripe-for-retirement' fleet relies on once-through cooling; 175 of the 295 remaining generators (59% of total capacity) use this technology, which has an average age of 47 years compared to 24 years for recirculating plants.
• EPA regulations, including the National Pollutant Discharge Elimination System and section 316(b) of the Clean Water Act, impose temperature limits and intake structure requirements that may force owners of once-through plants to invest in costly upgrades or retire the plants.
• Replacing both announced and 'ripe-for-retirement' coal generators with renewables and energy efficiency could avoid approximately 8,421 billion gallons of water withdrawals and 149 billion gallons of water consumption annually.
• Southern Company is the utility with the most 'ripe-for-retirement' generators using once-through cooling, owning 26 units totaling nearly 5.8 GW of capacity across Alabama, Florida, Georgia, and Mississippi.

APA

Union of Concerned Scientists (2013). Water Dependence Risks for America’s Aging Coal Fleet. https://www.ucs.org/sites/default/files/2019-09/Water-Dependence-Risks-for-America-s-Aging-Coal-Fleet.pdf

Chicago

Union of Concerned Scientists. Water Dependence Risks for America’s Aging Coal Fleet. 2013. https://www.ucs.org/sites/default/files/2019-09/Water-Dependence-Risks-for-America-s-Aging-Coal-Fleet.pdf.

Wikipedia

{{cite report |author=Union of Concerned Scientists |title=Water Dependence Risks for America’s Aging Coal Fleet |date=March 2013 |url=https://www.ucs.org/sites/default/files/2019-09/Water-Dependence-Risks-for-America-s-Aging-Coal-Fleet.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{unionofconcernedscientists2013water, author = {{Union of Concerned Scientists}}, title = {{Water Dependence Risks for America’s Aging Coal Fleet}}, institution = {Union of Concerned Scientists}, year = {2013}, month = mar, url = {https://www.ucs.org/sites/default/files/2019-09/Water-Dependence-Risks-for-America-s-Aging-Coal-Fleet.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }